Quick drying vehicle and method of drying same



United States Patent ice 7 3,013,895 QUICK DRYING VEHICLE AND METHOD OF DRYING SAME Meyer S. Agl'uss, Chicago, Ill., assignor to Miehle-Goss- Dexter, Incorporated, Chicago, 11]., a corporation of Delaware No Drawing. Filed Nov. 26, 1958, Ser. No. 776,450

I 14 Claims. (Cl. 117-38) This invention relates to the art of coating materials. It has particular reference to an improved quick-drying vehicle for various coatings and to an improved method for rapidly indurating or drying such a vehicle after the coating operation.

The term coating materials is intended to cover vehicles or materials which embrace the characteristics of the subject invention and which may have applications in fields other than those specifically mentioned herein, such as, for example, photosensitive resists for use in the graphic arts, plugging materials for use in the drilling operations encountered in the petroleum industries, and the. like. However, for illustrative purposes, and with no intent to limit its field of use, the invention will be described with particular reference to printing, wherein the coat-forming materialis applied by a conventional printing plate. 7

Prin'ting'inks as made heretoforeconsist mainly of a non-aqueous vehicle, namely a drying oil, pigmented to the desired color. The drying oils commonly used for printing inks, such as tung oil, linseed oil, rape seed oil, dehydrated castor oil and alkyds, have by nature a dry ing'rate which is slow compared to the potential op- Wendt will obviously result in an unstable product havwhich entails obvious disadvantages in commercial printing. Wendt'Patents Nos. 2,453,769 and 2,453,770 'disclose printing'inlrs containing certain methane derivatives for promoting polymerization of the drying oil, and irradiation of the p-rinted'm'aterial with ultraviolet light of certain wave lengths; but this expedient is admittedly unsuitable when a heat bodied tung oil is used as the vehicle and the use of pure 'eleostearin as suggested by ing too short a shelf life for commercial purposes; a

The vehicles described in copending applications, Ser; Nos. 557,865, 562,671 and 563,423, are a substantial improvement over the prior art drying oil compositions. However, they are limited to drying periods of about two seconds. Modern presses can operate at rates 'requiring a printing ink vehicle that will not smudge within a fraction of a second after application.

The principalobject of the present-invention is to provide a quick-drying vehicle and a method for rapidly in i vide an ink of this character which isi stable inthat it crating speeds of printing presses, even when the usual M driers (e.g. cobalt) are added to the oils. with the advent of the higher speed pressesand multiple color printing, the avoidance of smudges and oif-set on thesuccessive sheets coming from the printingpress has presented a serious problem.

Numerous attempts have been made to solve this probthe freshly printed surface (see Costell Patent No. 2,696,-

accessory equipment andis generally inconvenient.

It has also been proposed to increase the drying rate of printing inks by employing a catalyst or polymerization promoter in conjunction with heat'or radiation of certain light energy. These proposals likewise involve objectionable featureswhich have barred or' greatly limited their'cornmercial use. For example, a printing ink containing'a diacyl peroxide as the catalys't'will un- Particularly can be stored for a'long period of time 'u nder ordinary conditions without livering. (While; I have referred .in the above to sheet-fed presses, it will beunderstood that the invention is also applicable to web-fed presses.)

By a quick-drying vehicle, I' mean a vehicle which, when applied in a thin film of about two to four microns in thickness, as in printing, will dry or" set rapidlyf For example, Table I shows several of the: compositions of I this invention drying or setting in a fraction of a second;

' that is, the surface of the film when irradiated with cold energy, 'preferably ultra-violet light, becomes sufliciently dry so that in the case of; a printing ink, for'examplef, it will not off-set on succeeding sheets coming from the press. However, the drying action does'not stopafter derg ofs kinning and livering even after a short period of i 7 the ultrafvioletf'or activating energy is removed- On the contrary, in the' pr'actice of the present'invention we have found that within a period "of up t oabout l.0 'se'cond after such removal oi the activating-Zenergy, the poly merization or dryingaction has penetrated the entire l6 8, dated Decernber 7, 1954) also requires considerable film to Provide a film Whiiih'i's hard throughout-7 The quick-drying vehicle of the present invention consists essentiallyof any-unsaturated polyester, any vihyl type monomer such as, for'example, styrene, and any titanium oitho ester. l ha've found that compositions, comprising the above named groups'of compounds will yield, upon irradiation with-ultraviolet light for a period of less than 'asecond, a coating'that will 'not oifset or smudge; I have further found 'that'thesenew"veliicles will not liverforskin upon standing.- In other' 'words,

these vehicles havelgood shelf -lifei I I have also foundtliatunsaturated polyestersan d drying 'oils which are normally incompatible-are made ihis cible in the presence of an organic titanatepsothat th vehicle may: comprise'a substantial amount; of drying oil.

The reason for the extremely quick dryingproperty'of a n d Pe 1 3 compositions containing an unsaturated polyester, a vinyltype monomer and a titanium ortho ester is not entirely clear. It is suspected that the vinyl monomer attaches through addition type polymerization to the unsaturated bonds of the polyester to cause cross-linking. The role that the titanate plays in bringing about the desired coating is obscure, but without the titanate ester the quickdrying characteristic of the vehicle is absent.

The unsaturated polyester may be made by the esterification of a polyhydric alcohol and a polybasic acid, one or both of which contains a double bonded pair of carbon atoms, the double bond rendering the polyester capable of subsequent cross-linking. The unsaturated polyester is usually blended with areactive cross-linking monomer, such as styrene, so that the mass upon being subject to polymerization condition forms a thermosetting resin.

The polyhydric alcohols most commonly used are glycolsof ethylene, propylene, 1,3-2,3-butylene, diethylene and dipropylene. Unsaturated dihydric alcohols are presently not readily available; therefore, the double bond is generally supplied by the dibasic acid. Acids such as maleic anhydride and fumaric acid are satisfactory.

Suitable monomers are styrene, vinyl toluene, methyl methacrylate, or admixtures of these monomers with either diallyl phthalate or triallyl cyanurate.

The viscosity of the polyester-monomer composition should be such that the vehicle will spread and flow relatively easily. Viscosities of 2000-4000 centipoises have been found satisfactory. The vinyl monomer is preferably present to the extent of about -70% of'the polyester.

Example of suitable organic titanates are tetraisopropyltitanate, tetra-n-butylti-tanate, tetra Z-ethylhexyltitanate and tetra stearyltitanate. The titanate should be present in about the proportion of 0.2 to 1.5 parts of titanate per part of polyester, with a preferred range of 0.4 to 0.8.

The ultra-violet light used to trigger the polymerization reaction is preferably the full spectrum of ultra-violet, including 1800 A. to 4000 A., as we have found that isolated bands of the spectrum do not provide as rapid a polymerization as the full spectrum. An example of such a light source is a high pressure electronic discharge quartz mercury arc tube having an active length of about 1 /2 inches and drawing about 100 watts, the ultra-violet intensity of radiations of 3130 A. and shorter, measured at 20 inches distance, being over 250 microwatts per square centimeter.

The method of the invention comprises essentially the rapid induration of the vehicle by (1) forming a solution of the polyester, monomer and titanate, (2) forming a film of the resulting solution, and (3) irradiating the film with cold energy (preferaby ultra-violet light).

It is to be understood that in the practice of this invention the desired pigment may be added to the vehicle. Likewise, materials imparting a better press stability characteristic to the vehicle may be added without materially affecting the drying time. Examples of suitable stabilizing materials are chlorinated parafiin wax, ethylene glycol dibenzoate, N-methyl morpholine and methyl cellosolve acetate.

In the preferred practice ofthis invention, the vehicle containing the pigment in the desired proportion is applied in any suntable manner as a film to the material to be coated, such as a paper, and is then irradiated with the ultra-violet light to'trigger the polymerization reaction.

When preparing the-vehicle of this invention, it is preferable to add the organic titanate to the unsaturated polyester containing the monomer. Upon first adding the titanate a thick, gelatinous, sticky mass results. Allowing this mass to stand overnightresults in the formation of a clear liquid. The formation of the clear liquid may be hastened by agitation.

Table I shows the drying times of vehicles of this inven tion when a thin film' of the vehicle is irradiated.

Table l Drying Vehicle Percent Time,

by Wt. Seconds Polyester 61. 5 0.003 I. Styrene 20.5 See-Butyltitanate 18.0

48.0 0.003 II. 32.0 20.0 54.0 0.003 III. 36.0 10.0 60.0 0.003 IV. 15.0 25.0 36.0 0.003 V. 24.0 40.0 48.0 0.003 VI. 12.0 40.0 48. 75 0.030 VII. 16.25 35.00 P lyestei 45.8 0.003

15. VIII S yrene 10.0 30.0 48.0 0.003 IX. yr ne 32.0 20.0 0.003

28.84 Raw tnng oil 13. 46 Ethylene glycol maleate polyester 54.0 XI (40% styrene modified).

' Styrene 36.0 .003

Sec.-Butyl titanate 10. 0

I claim:

1. A stable quick-drying vehicle for coating materials comprising an unsaturated polyester, a vinyl-type monomer capable of undergoing addition polymerization with the unsaturated polyester, and a titanium orthoester, said polyester vinyl monomer and titanium orthoester being adapted to quick drying when exposed in a thin film to cold energy.

2. A vehicle according to claim 1, in which the monomer is present in an amount approximately 10% to 70% by weight of the polyester.

3. A vehicle according to claim 1, in which the titanium orthoester is present in an amount approximately 20% to by weight of the polyester.

4. A vehicle according to claim 1, in which the monomer is styrene.

5. A vehicle according to claim 1, in which the titanium orthoester is sec.-butyltitanate.

6. A stable quick-drying vehicle for coating materials, comprising an unsaturated polyester, a vinyl-type monomer capable of undergoing addition polymerization with the unsaturated polyester, a drying oil and a titanium orthoester, said vehicle being adapted to quick drying when exposed in a thin film to cold energy.

7. A vehicle according to claim 6, in which the drying oil is present in an amount which is approximately 30% by weight of the polyester.

8. A stable quick-drying printing ink, comprising an unsaturated polyester, a vinyl-type monomer capable of undergoing addition polymerization with the unsaturated polyester, a titanium orthoester and a pigment, said ink being adapted to quick drying when exposed in a thin film to cold energy. 9. A method for rapidlyindurating a vehicle comprising an unsaturated polyester, a vinyl-type monomer capable of undergoing addition polymerization with the unsaturated polyester and a titanium orthoester, which comprises forming a solution of the polyester, monomer and titanate, forming a film of said solution, and irradiating said film with cold energy.

'10. The method according to claim 9, in which said cold energy is ultra-violet light.

11. The method according to claim 9, in which said cold energy is the full spectrum of ultra-violet light.

12. In the art of printing a sheet, the improvement which comprises forming a solutionof an unsaturated polyester, a vinyl-type monomer capable of undergoing addition polymerization with the unsaturated polyester, and a titanium orthoester, said solution having suspended therein a pigment to form an ink, printing the sheet with said ink, and irradiating the printed surface of the sheet with cold energy.

13. The improvement according to claim 12, in which said cold energy is ultra-violet light.

14. The improvement according to claim 12, in which References Cited in the file of this patent UNITED STATES PATENTS Wendt Nov. 16, 1948 Kropa et a1 Dec. 19, 1950 Schmutzler Mar. 25,1952 Wakeford Aug. 19, 1952 Meeske July 28, 1953 Hahn July 28, 1953 Kronstein June 8, 1954 

1. A STABLE QUICK-DRYING VEHICLE FOR COATING MATERIALS COMPRISING AN UNSATURATED POLYESTER, A VINYL-TYPE MONOMER CAPABLE OF UNDERGOING ADDITION POLYMERIZATION WITH THE UNSATURATED POLYESTER, AND A TITANIUM ORTHOESTER, SAID POLYESTER VINYL MONOMER AND TITANIUM ORTHOESTER BEING ADAPTED TO QUICK DRYING WHEN EXPOSED IN A THIN FILM TO COLD ENERGY. 